########################## MusicBrainz Database Tools ########################## |pypi badge| |ci badge| .. |pypi badge| image:: https://badge.fury.io/py/mbdata.svg :target: https://badge.fury.io/py/mbdata .. |ci badge| image:: https://code.oxygene.sk/lukas/mbdata/badges/master/pipeline.svg :target: https://code.oxygene.sk/lukas/mbdata/commits/master **************************** MusicBrainz Database Replica **************************** This repository now contains a collection of scripts for managing a replica of the MusicBrainz database. These used to be called "mbslave", but have been moved to this repository. The main motivation for these scripts is to be able to customize your database. If you don't need such customizations, it might be easier to use the replication tools provided by MusicBrainz itself. Installation ============ 1. Make sure you have `Python <https://python.org/>`__ and `psycopg2 <https://initd.org/psycopg/>`__ installed. On Debian and Ubuntu, that means installing these packages:: sudo apt install python python-pip python-psycopg2 pip install -U mbdata # if you don't have it installed already The command will install the ``mbslave`` script into ``$HOME/.local/bin``. 2. Get an API token on the `MetaBrainz website <https://metabrainz.org/supporters/account-type>`__. 3. Create mbslave.conf by copying and editing `mbslave.conf.default <https://github.com/lalinsky/mbdata/blob/master/mbslave.conf.default>`__:: curl https://raw.githubusercontent.com/lalinsky/mbdata/master/mbslave.conf.default -o mbslave.conf vim mbslave.conf By default, the ``mbslave`` script will look for the config file in the current directory. If you want it to find it from anywhere, either save it to ``/etc/mbslave.conf`` or set the ``MBSLAVE_CONFIG`` environment variable. For example::: export MBSLAVE_CONFIG=/usr/local/etc/mbslave.conf 4. Setup the database. If you are starting completely from scratch, you can use the following commands to setup a clean database:: sudo su - postgres createuser musicbrainz createdb -l C -E UTF-8 -T template0 -O musicbrainz musicbrainz createlang plpgsql musicbrainz psql musicbrainz -c 'CREATE EXTENSION cube;' psql musicbrainz -c 'CREATE EXTENSION earthdistance;' 5. Prepare empty schemas for the MusicBrainz database and create the table structure:: echo 'CREATE SCHEMA musicbrainz;' | mbslave psql -S echo 'CREATE SCHEMA statistics;' | mbslave psql -S echo 'CREATE SCHEMA cover_art_archive;' | mbslave psql -S echo 'CREATE SCHEMA wikidocs;' | mbslave psql -S echo 'CREATE SCHEMA documentation;' | mbslave psql -S mbslave psql -f CreateCollations.sql mbslave psql -f CreateTables.sql mbslave psql -f statistics/CreateTables.sql mbslave psql -f caa/CreateTables.sql mbslave psql -f wikidocs/CreateTables.sql mbslave psql -f documentation/CreateTables.sql 6. Download the MusicBrainz database dump files from http://ftp.musicbrainz.org/pub/musicbrainz/data/fullexport/ 7. Import the data dumps, for example:: mbslave import mbdump.tar.bz2 mbdump-derived.tar.bz2 8. Setup primary keys, indexes and views:: mbslave psql -f CreatePrimaryKeys.sql mbslave psql -f statistics/CreatePrimaryKeys.sql mbslave psql -f caa/CreatePrimaryKeys.sql mbslave psql -f wikidocs/CreatePrimaryKeys.sql mbslave psql -f documentation/CreatePrimaryKeys.sql mbslave psql -f CreateIndexes.sql mbslave psql -f CreateSlaveIndexes.sql mbslave psql -f statistics/CreateIndexes.sql mbslave psql -f caa/CreateIndexes.sql mbslave psql -f CreateFunctions.sql mbslave psql -f CreateViews.sql 9. Vacuum the newly created database (optional):: echo 'VACUUM ANALYZE;' | mbslave psql Replication =========== After the initial database setup, you might want to update the database with the latest data. The `mbslave sync` script will fetch updates from MusicBrainz and apply it to your local database:: mbslave sync In order to update your database regularly, add a cron job like this that runs every hour:: 15 * * * * mbslave sync >>/var/log/mbslave.log Schema Upgrade ============== When the MusicBrainz database schema changes, the replication will stop working. This is usually announced on the `MusicBrainz blog <http://blog.musicbrainz.org/>`__. When it happens, you need to upgrade the database. 2020-05-18 Upgrade to PostgreSQL 12 ----------------------------------- These steps are recommended even if you were already running on Postgres 12 before MusicBrainz moved to make PostgreSQL 12 the minimal supported version. Run the pre-upgrade script:: mbslave psql -f updates/20200518-pg12-before-upgrade.sql If not already on PostgreSQL 12, upgrade your cluster now (depending on your OS, using `pg_upgradecluster` or `pg_upgrade`) After upgrading, or if already on PostgreSQL 12, run:: mbslave psql -f updates/20200518-pg12-after-upgrade.sql Release 2019-05-14 (25) ~~~~~~~~~~~~~~~~~~~~~~~ Run the upgrade scripts:: mbslave psql -f updates/schema-change/25.slave.sql echo 'UPDATE replication_control SET current_schema_sequence = 25;' | mbslave psql Release 2017-05-25 (24) ~~~~~~~~~~~~~~~~~~~~~~~ Run the upgrade scripts:: mbslave psql -f updates/schema-change/24.slave.sql echo 'UPDATE replication_control SET current_schema_sequence = 24;' | mbslave psql Tips and Tricks =============== Single Database Schema ~~~~~~~~~~~~~~~~~~~~~~ MusicBrainz uses a number of schemas by default. If you are embedding the MusicBrainz database into an existing database for your application, it's convenient to merge them all into a single schema. That can be done by changing your config like this:: [schemas] musicbrainz=musicbrainz statistics=musicbrainz cover_art_archive=musicbrainz wikidocs=musicbrainz documentation=musicbrainz After this, you only need to create the "musicbrainz" schema and import all the tables there. Full Import Schema Upgrade ~~~~~~~~~~~~~~~~~~~~~~~~~~ You can use the schema mapping feature to do zero-downtime upgrade of the database with full data import. You can temporarily map all schemas to e.g. "musicbrainz_NEW", import your new database there and then rename it:: echo 'BEGIN; ALTER SCHEMA musicbrainz RENAME TO musicbrainz_OLD; ALTER SCHEMA musicbrainz_NEW RENAME TO musicbrainz; COMMIT;' | mbslave psql -S ***************** SQLAlchemy Models ***************** If you are developing a Python application that needs access to the `MusicBrainz <https://musicbrainz.org/>`__ `data <https://musicbrainz.org/doc/MusicBrainz_Database>`__, you can use the ``mbdata.models`` module to get `SQLAlchemy <http://www.sqlalchemy.org/>`__ models mapped to the MusicBrainz database tables. All tables from the MusicBrainz database are mapped, all foreign keys have one-way relationships set up and some models, where it's essential to access their related models, have two-way relationships (collections) set up. In order to work with the relationships efficiently, you should use the appropriate kind of `eager loading <http://docs.sqlalchemy.org/en/latest/orm/loading_relationships.html>`__. Example usage of the models: .. code:: python >>> from sqlalchemy import create_engine >>> from sqlalchemy.orm import sessionmaker >>> from mbdata.models import Artist >>> engine = create_engine('postgresql://musicbrainz:musicbrainz@127.0.0.1/musicbrainz', echo=True) >>> Session = sessionmaker(bind=engine) >>> session = Session() >>> artist = session.query(Artist).filter_by(gid='8970d868-0723-483b-a75b-51088913d3d4').first() >>> print artist.name If you use the models in your own application and want to define foreign keys from your own models to the MusicBrainz schema, you will need to let ``mbdata`` know which metadata object to add the MusicBrainz tables to: .. code:: python from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() # this should be the first place where you import anything from mbdata import mbdata.config mbdata.config.configure(base_class=Base) # now you can import and use the mbdata models import mbdata.models You can also use ``mbdata.config`` to re-map the MusicBrainz schema names, if your database doesn't follow the original structure: .. code:: python import mbdata.config mbdata.config.configure(schema='my_own_mb_schema') If you need sample MusicBrainz data for your tests, you can use ``mbdata.sample_data``: .. code:: python from mbdata.sample_data import create_sample_data create_sample_data(session) ******** HTTP API ******** **Note:** This is very much a work in progress. It is not ready to use yet. Any help is welcome. There is also a HTTP API, which you can use to access the MusicBrainz data using JSON or XML formats over HTTP. This is useful if you want to abstract away the MusicBrainz PostgreSQL database. Installation: .. code:: sh virtualenv --system-site-packages e . e/bin/activate pip install -r requirements.txt python setup.py develop Configuration: .. code:: sh cp settings.py.sample settings.py vim settings.py Start the development server: .. code:: sh MBDATA_API_SETTINGS=`pwd`/settings.py python -m mbdata.api.app Query the API: .. code:: sh curl 'http://127.0.0.1:5000/v1/artist/get?id=b10bbbfc-cf9e-42e0-be17-e2c3e1d2600d' For production use, you should use server software like `uWSGI <http://projects.unbit.it/uwsgi/>`__ and `nginx <http://nginx.org/>`__ to run the service. ********** Solr Index ********** Create a minimal Solr configuration: .. code:: sh ./bin/create_solr_home.py -d /tmp/mbdata_solr Start Solr: .. code:: sh cd /path/to/solr-4.6.1/example java -Dsolr.solr.home=/tmp/mbdata_solr -jar start.jar *********** Development *********** Normally you should work against a regular PostgreSQL database with MusicBrainz data, but for testing purposes, you can use a SQLite database with small data sub-set used in unit tests. You can create the database using: .. code:: sh ./bin/create_sample_db.py sample.db Then you can change your configuration: .. code:: sh DATABASE_URI = 'sqlite:///sample.db' Running tests: .. code:: sh nosetests -v If you want to see the SQL queries from a failed test, you can use the following: .. code:: sh MBDATA_DATABASE_ECHO=1 nosetests -v Jenkins task that automatically runs the tests after each commit is `here <http://build.oxygene.sk/job/mbdata/>`__.